Abstract
BACKGROUND Whereas non-tuberculous mycobacterium (NTM) pulmonary disease can mimic lung cancer as a solitary pulmonary nodule or mass, the coexistence of lung cancer and NTM pulmonary disease in a single nodule or mass is rare. We report such a rare case, highlighting that during a bronchoscopes examination which comprises taking a transbronchial lung biopsy (TBLB), bronchial brushing, and bronchial lavage, a positive mycobacterium culture result for sputum or bronchial lavage fluid does not exclude the possibility of a concomitant lung cancer. CASE REPORT An 87-year-old male was referred to our institution for evaluation of an abnormal shadow on a chest x-ray scan. He had been previously healthy with no symptoms and an unremarkable medical history. A contrast-enhanced CT scan showed a cavitating mass measuring 20×40 mm with a thick ring-enhancing irregular wall in the left lower lobe. Although the TBLB of the lesion showed no malignant cells, sputum acid-fast bacilli smear and culture of the bronchial lavage fluid yielded positive results. An NTM infection, instead of lung cancer was suspected to have caused the mass because a Mycobacterium tuberculosis polymerase chain reaction showed negative results. However, we performed the surgery because NTM pulmonary disease and lung cancer cannot be differentiated. The results of a pathological examination of the mass showed an adenocarcinoma, and M. avium complex was detected in the cancer tissue culture. CONCLUSIONS Physicians should suspect the co-existent lung cancer and NTM infection in patients with solitary lung masses that yield a positive mycobacterium culture result for sputum or bronchial lavage fluid.